Method and apparatus for displaying 3d images

ABSTRACT

The invention relates to a method for displaying three-dimensional images. In the method light beams (L e ) are associated to several different screen points (P) of a screen ( 20 ). The light beams (L e ) produce different views associated to different emission directions (E). The emission directions (E) are associated to the individual screen points (P). The light beams (L e ) are generated by projecting light beams (L d ), according to the angle of the adjacent emitting directions. According to the invention, light beams (L e ) without viewing direction information are generated, essentially simultaneously, with pixels (C d ) having different co-ordinates. These pixels (C d ) are pixels of a two-dimension display ( 50 ), and they are associated to different emitting directions (E) of the appropriate screen points (P). The light beams (L e ) produced by the pixels (C d ) of the display ( 50 ) with different co-ordinates are imaged simultaneously in different deflection directions (D), as a function of the co-ordinates of the pixels (C d ) producing the light beams (L e ). The subject of the invention is an apparatus implementing the above method.

TECHNICAL FIELD

[0001] The invention relates to a method for displaying 3D images, inthe course of which light beams associated to multiple different pointsof a screen and light beams creating different views associated todifferent emitting directions of the individual screen points aregenerated, and the light beams thus generated are projected onto adirectionally selective transmitting and/or reflecting screen. Thesubject of the invention also relates to the apparatus implementing themethod of the invention. The apparatus comprises a screen for directionselectively transmitting and/or reflecting light, and a screenilluminating system. The screen illuminating system comprises modulesfor generating light beams; the light beams being associated to multipledifferent points of the screen, and to different emitting directions ofthe points of the screen. The modules are controlled by an appropriatecontrol system.

BACKGROUND ART

[0002] Three dimensional (3D) imaging methods based on the aboveprinciples are described in detail in the documents no. WO 94/23541 andWO98/34411, the contents of which is presumed to be known forunderstanding the present invention. 3D images contain more informationthan 2D images. To display a 3D image, an appropriate number of screenpoints (spots) must be generated, and, in the case of a moving image,taking into consideration the change of the frames, an appropriatespot/sec ratio must be generated as well. The number of screen points(spots) is basically the product of the image resolution and the angleresolution (that is, the number of distinguishable views or viewingzones). In addition, in the case of a moving image, the number of screenpoints required within one single frame must be multiplied by the numberof frames changed in one second (frame/sec), thus giving the number ofscreen points to be generated every second.

[0003] The basic problem is how to generate the required number ofimaging screen points (spots) within a given unit of time (spot/sec):

[0004] One possible solution is to perform the multiplication with thetime; in which case faster devices are needed, as it is described inU.S. Pat. No. 6,157,424. Such a device is not yet available in practice,or is only able to display a limited number of views. These devicesapply fast LCD screens or other fast light valves, placed in two orthree subsequent planes.

[0005] The second solution is spatial division, that is, the requirednumber of screen points are generated paralelly and appropriatelyorganised. In practice, displays of normal speed must be used, but witha greater number of pixels (high resolution), or more displays withnormal resolution. The disadvantage of this approach is that it requiresmore space. Such are lenticular systems, where different directions arecreated at the expense of resolution; for example, to create tendirections a device with a 10-fold resolution is needed, where everytenth screen point is associated to a certain direction, or,alternatively, a screen (display) is divided into ten parts. Differentversions of these solutions are now known.

[0006] The third possibility is to combine the two methods, makingoptimal use of the speed and resolution of the devices, taking intoconsideration the technological features and limitations of the screenpoint generating element; for example, for generating 30 views, tenpieces of triple-speed devices or with a ten-fold resolution areapplied. The spatially separated the 10-fold number of screen points isdivided in time by 3 different light sources—typically from differentdirections.

[0007] The present invention describes a method and apparatus, whichmeet the above requirements, with a method that can be realised withreal, existing technologies, based on the second and third solutions.

[0008] The purpose of the present invention is to provide an improvedmethod and apparatus which can produce high quality colour images withadequately high frame frequency, that is, which makes it possible toproduce moving 3D colour images, as well. To solve this task, theinvention basically requires a new optical arrangement.

[0009] An important element of the known 3D imaging systems describedabove is a relatively small light source emitting light beams of varyingintensity (and preferably of different colours) in different directions.In document no. WO 98/3441 this is created through an acousto-opticaldeflector which deflects and modulates a laser beam as a function oftime. Thus light beams are generated and emitted in differentdirections, and these light beams are differently modulated in differentdirections.

SUMMARY OF THE INVENTION

[0010] According to the invention, these light beams arc generated in amanner different from the known methods. In the method according to theinvention, light beams substantially without emitting directioninformation are generated, substantially simultaneously, with the pixelsof a two-dimensional display, where the pixels have differentco-ordinates. The light beams are associated to the different points onthe screen, and correspond to the different emitting directions of thescreen points.

[0011] The light beams generated by the display pixels with differentco-ordinates are imaged substantially simultaneously into differentdeflecting directions. The imaging is performed as a function of theco-ordinates of the pixels generating the light beams.

[0012] In a preferred implementation of the method, the light beamsprojected in different directions towards the screen points are createdby generating a composite image. This composite image comprises suchimage details, which correspond to the images to be projected intodifferent directions from the different screen points. The compositeimages are illuminated with substantially parallel light beams. Thegenerated substantially parallel light beams are modulated with theintensity and/or colour information of the individual image details. Themodulated substantially parallel light beams are projected onto anoptical deflecting means, preferably onto an imaging optics, e.g. anobjective lens with a large angle of incidence. The projecting isperformed in the function of the spatial coordinates. The substantiallyparallel light beams, which are modulated with the image details of thecomposite image, are projected with the optical deflecting means towardsthe appropriate screen points. The projection is performed by deflectingthe light beams into different directions. The deflection is madeaccording to the position of the relevant image details on the compositeimage, and the imaging properties of the optical deflecting element. Inthis manner the appropriate screen points are defined by the mutualposition of the relevant modules (comprising the relevant opticaldeflecting means) and the screen.

[0013] The subject of the invention is also an apparatus for the displayof three-dimensional images, as described in the introduction. Theapparatus comprises a screen for direction selectively transmittingand/or reflecting light, and a screen illuminating system. According tothe invention, the modules further comprise a two-dimensional display,and an optical system for simultaneously imaging the individual pixelsof the display onto the screen. The display pixels on thetwo-dimensional display are associated to the different points on thescreen, and at the same time correspond to the different emittingdirections, the emitting directions also being associated to thedifferent screen points. The display pixels generate substantiallysimultaneously light beams with different co-ordinates but substantiallywithout emitting direction information. The imaging optics associated tothe display substantially simultaneously images the light beamsgenerated by the display pixels with different co-ordinates intodifferent emitting directions or imaging directions.

[0014] Preferably, the screen transmits the incoming light beamssubstantially without changing their direction or reflects the lightbeams in a mirror-like manner or retroreflectively. At the same time,the modules are realised as means for generating light beams, which arethen emitted in different directions from the screen points. For thispurpose, the modules project light beams with different intensity and/orcolour towards the individual screen points from different directions.Thus in the means for projecting light beams towards the screen points,the two dimensional display functions as an image generating means forgenerating a composite image, where the composite image is composed ofthe image details to be projected into the different emitting directionsfrom the different screen points. Hereafter such a composite image isalso termed as a module image, because it is normally generated by thedisplay of a module. The imaging optics of the apparatus also comprisesmeans for deflecting the light beams incoming onto the imaging opticswith a given angle, so that this deflection angle is a function of theincoming co-ordinates of the light beam. The imaging optics preferablycomprises an optical lens.

[0015] At the same time, the illuminating system is provided with meansfor generating substantially parallel, and—as a function of the spatialco-ordinates—substantially homogenous light beams for illuminating theimage generating means.

[0016] In the optical system the modules are positioned relative to eachother and to the screen, so that the light beams, which are coded withthe pixels of a composite image—preferably by modulating with colour-and intensity information—are deflected by the optical deflecting meanstowards the different deflection directions and towards the appropriatescreen points, according to the mutual position of the relevant modulesand the screen.

[0017] The screen, on the other hand, provides an appropriate lightdivergence, according to the angle between the light beams projected onthe same screen point from the adjacent modules. The divergence isprovided in a plane determined by the light beams.

[0018] Preferably, the image generating means is a micro-display. Theintegrated circuit technology has made the production of the abovedevices in smaller size—practically in the size of an IC—usually with apixel size of 10-15 microns with higher resolution and at lower costs.This makes recommended large number parallel operating micro-displaybased systems/apparatus feasible.

[0019] With one of the proposed embodiments, the two-dimensional displayis also a ferroelectric liquid crystal microdisplay (FLC microdisplay).These are available in small sizes, colour version and in large numbers.However, their size is still larger than the characteristic distance ofthe screen points of the screen. Therefore, for a preferable realisationof the invention we recommend the use of fewer two-dimensional displaysthan the number of screen points of the screen. A further problem iscaused by the effective area of the displays always being smaller thantheir entire area. In the case of some optical arrangements the physicalsize of the displays determines the number of emitting directions, thatis the angle resolution of the apparatus. In order to increase thenumber of the emitting directions, the two-dimensional displays arepositioned in several parallel rows and shifted parallel to the rowscompared to each other. This way a virtually united, long display isobtained, which can provide a high angle resolution three-dimensionalimage, with good depth of field, and the horizontal resolution of thedisplays can also be fully exploited.

[0020] It has also proven practical for the apparatus to contain severaldevices producing essentially parallel light beams, which have a commonlight source, preferably any intensive light source, mirror light bulbsor metal-halide lamps. This way the light of the common light source isdirected to the individual optical deflection devices through opticalfibres. This significantly simplifies the structure of the lightingsystem, the distribution of the light to the large number of modules,and the light source can be placed further from the lenses and itscooling can be better implemented.

[0021] The continuous appearance of the three-dimensional image from anydirection is served by the solution of using an optical plate, whichfunctions as the screen for providing divergence to the directionselectively transmitted or reflected light. The divergence of theoptical plate is preferably provided by a lens system or a holographiclayer.

[0022] It is also viable in some applications that the screen provides aretroreflective surface. This arrangement is advantageous, when theobserver of the three-dimensional image moves in a relatively narrowspace and the different views are to be created within that space only.

[0023] For example, if the screen is located somewhere on a circle whichis essentially concentric with a circle created by the modules, then thethree-dimensional image is mainly visible in the area around the centreof the circles, but has a very good directional resolution in that area.This means that the change of the view is also perceptible if theobserver moves only slightly.

[0024] The invention eliminates the theoretical disadvantage of knownsystems operating on a three-dimensional parallel display theory in thatit uses significantly smaller image point generating means than thefinal 3D (complex) image. The image point generating means are used inan appropriate geometry. This can help avoid the sub-pixel structurethat lead to bad filling (the so-called stadium display or fence effect,resolution reduction, etc.). Light passes light beams without obstacleand is emitted from the same (screen) point instead, when using theimage generating method in accordance with the invention.

[0025] A technological limitation of traditional display systems is howto achieve high lamp power: the light intensity that can be concentratedon the LCD panel poses a limit for the largest lamp power projectors,while smaller projectors can also use high performance light sources toproduce images visible in average illumination with all its knownconsequences, such as cooling, etc.

[0026] In the ease of the apparatus based on a large number ofmicrodisplays in accordance with the invention the above obstacle can beovercome. Complex, high light power 3D images can be generated, so thatthe limited light bearing capacity LCD panels have to transmit and/orreflect lower light intensity in proportion to their number, i.e. in thecase of a 100 panel system the light intensity is only oneone-hundredth. On the other hand, it is possible to produce images withsimilar brightness as with traditional apparatus by using several, lowerbrightness, but effective light sources, such as LEDs due to theparallel distribution structure.

[0027] Preferably, the apparatus according to the invention has severalmeans for generating essentially parallel light beams, which either haveseparate light sources (LEDs, LED matrixes) or a common light source.The light from the common light source is distributed by optical fibres,multicore randomised head bundles or other light lines and led to theoptical modules/units containing the microdisplay. The colour control ofthe common light source, such as a metal-halide lamp is carried out witha known method, e.g. by colour filters and shutters dividing the lightinto RGB channels, or by colour discs

BRIEF DESCRIPTION OF DRAWINGS

[0028] By way of example only, an embodiment of the invention will nowbe described with reference to the accompanying drawing, in which

[0029]FIGS. 1 and 2 demonstrate the basic principle of the apparatus andmethod of 3D image display of the invention;

[0030]FIG. 3. is the scheme of the basic elements of the imaging systemof the invention as well as a functional scheme demonstrating the basicprinciple of the optical lens system;

[0031]FIG. 4. the enlarged cross-section of the screen from FIGS. 1-3with the scheme demonstrating light divergence;

[0032]FIG. 5. shows the way light beams produced by the apparatus withthe modules in FIG. 3, in the case of observers watching the apparatusfrom a given position;

[0033]FIG. 6. presents the image display principle of the apparatusaccording to the invention;

[0034]FIG. 7a. is a partial front and top view perspective of the screenin FIG. 4;

[0035]FIGS. 7b. and 7 c. demonstrating the difference between twodifferent realisations of the 3D image display system according to theinvention, in views similar to FIG. 7a,

[0036]FIG. 8. illustrates the three-dimensional arrangement of the partsfor one embodiment of the apparatus of the invention;

[0037]FIG. 9. is a side view of the imaging system of FIG. 3;

[0038]FIG. 10. similar to FIG. 8, another embodiment of the apparatus ofthe invention;

[0039]FIG. 11. shows the optical system of the arrangement of FIG. 10from a similar view as FIG. 9;

[0040]FIG. 12. a theoretical scheme of a modified version of the imagingsystem that illustrates several image generating means with one display;

[0041]FIG. 13. illustrates the optical system of the image generatingmeans created according to FIG. 12;

[0042]FIG. 14. a version of the optical system of FIG. 13;

[0043]FIG. 15. another version of the optical system of FIG. 13;

[0044]FIG. 16. illustrates a further version of several image generatingmeans equipped with a single display, where distribution is not spatial,but in a time sequence;

[0045]FIG. 17. illustrates the relative position of the individual imagegenerating means towards each other when placed in several rows;

[0046]FIG. 18. illustrates the optically symmetric arrangement of theindividual modules and the screen;

[0047]FIG. 19. illustrates another version of the optically symmetricarrangement of the individual modules and the screen;

[0048]FIG. 20. illustrates another version of the optically symmetricarrangement of the individual modules and the screen;

[0049]FIG. 21. illustrates another version of the optically asymmetricarrangement of the individual modules and the screen;

[0050]FIG. 22. illustrates the principle of the optical arrangementapplied in the individual modules;

[0051]FIG. 23. an improved version of the realisation of the imagegenerating means;

[0052]FIG. 24. top view of the arrangement of FIG. 23;

[0053]FIG. 25. another realisation of the optical system used in themodules, shown in a view perpendicular to the optical axis;

[0054]FIG. 26. a modified version of the optical system of FIG. 25;

[0055]FIG. 27. a perspective, theoretical view of a version of theoptical system of FIG. 25;

[0056]FIG. 28. the principle of another version of the screen with therelated module arrangement, and showing the structure of the screen;

[0057]FIG. 29. illustrating a practical application of the arrangementin FIG. 28;

[0058]FIG. 30. a perspective and cross-sectional view of a possibleembodiment of the screen from two angles;

[0059]FIG. 31. shows the cross-section of another embodiment of thescreen;

[0060]FIG. 32. shows another embodiment of the screen from the same viewas FIG. 31;

[0061]FIG. 33. illustrates another possible embodiment of the screenfrom the same view as

[0062]FIG. 30;

[0063]FIG. 34. the section of the screen in FIG. 33;

[0064]FIG. 35. the section of the screen in FIG. 33 with a additionalscreen;

[0065]FIG. 36. the section of the screen in FIG. 33 with another type ofadditional screen;

[0066]FIG. 37. the section of the screen in FIG. 33 with a surfaceconfiguration performing the functions of the accessory screen in FIG.35;

[0067]FIG. 38. the perspective view of another embodiment of theinventive apparatus;

[0068]FIG. 39. illustrates a way of application for the apparatus inFIG. 38;

[0069]FIG. 40. illustrates another way of application for the apparatusin FIG. 38;

[0070]FIG. 41. a partly cutout view illustrating the basic structure ofthe apparatus in FIG. 38;

[0071]FIG. 42. a further version for the concrete realisation of themodules used in the apparatus with a similar scheme as in FIG. 22;

[0072]FIG. 43. the perspective view of the LED lighting unit used in themodule shown in

[0073]FIG. 42;

[0074]FIG. 44. shows the organisation of the light spots of the lightingunit in FIG. 43; and finally

[0075]FIG. 45. demonstrates the functional construction of the controlsystem controlling the operation of the display apparatus of theinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0076] With reference to FIGS. 1-3 we explain the principle of theinvention through presenting the apparatus. The apparatus is to providethree-dimensional images with a sense of space. This is fulfilled by thescreen of the apparatus emitting different light beams in differentemitting directions as explained in detail in FIG. 6. For that purposethe apparatus has a screen 20 that transmits and/or reflects lightdirection selectively. By the direction selectivity of the screen wemean that the exiting light beam L_(c) exits the screen 20 depending ofthe incident angle of the deflected light beam L_(d) arriving at thescreen 20, i.e. a well defined emitting angle is associated to a givenincident angle. In other words, the direction of the incident light beamL_(d) explicitly determines the direction of the exiting light beamL_(e), as opposed to diffuse screens, where after the incidence of alight beam other light beams exit in a relatively wide space angle andthe direction of the incident exciting beam cannot be determined from alight beam exiting in a given direction.

[0077] There are screen points P in the screen 20, which are notnecessarily physically distinguished, that is their position isdetermined by the incident and emergent light beams in a given case Itis also viable, however that the position of the screen points P is alsophysically fixed in the screen, for example 20 with appropriateapertures. In such cases the screen points P can also be physicallyseparated by a borderline 21 between the screen points P in FIG. 4. Inmost cases, like the described examples the direction selectivity of thescreen 20 is realised so that the screen 20 transmits the light beamsL_(d) arriving at the screen points P without changing their directionsor reflects the light beams L_(d) like a mirror.

[0078] The screen points P of the screen 20 can emit colours ofdifferent intensity and/or colour in different directions. This featureof the screen 20 facilitates the apparatus to operate as athree-dimensional display. FIGS. 1-3 demonstrate an embodiment, wheretight beams L_(d) practically do not change their direction when passingthrough the screen 20 and exit as light beams L_(c) within the emittingangle range α. It is to be emphasised that the geometrical proportionsof the arrangement in the figures do not correspond to the real size ofthe apparatus, the drawings are only to explain the working principle.

[0079] The following annotation convention is used in the following partof the description: We assume that there are q number of modules in theapparatus, where we mark an arbitrary module with an intermediate indexj from one of the l . . . q modules. A module can emit light in ndifferent directions, the annotations for the arbitrary intermediatedirections are i, m or g. There are p number of screen points P in thescreen 20, the intermediate index is k. Light can emerge from a screenpoint P in n* emitting directions, this way n* emitting directions canbe associated to a P screen point, that is to the whole screen 20. Theintermediate indexes used here are i*, m* or g*. In the case of lightbeams, the lower index (s, c, d, e) refers to the function of the lightbeam in the optical system, where L_(s) represent light beams emitted bythe light source, L_(c) represent collimated light beams, L_(d)represent deflected light beams, and L_(e) represent the light beamsfinally emitted from the screen 20 towards the observer. The upperindexes refer to the module in line, the emitting direction related tothe module and the concerned screen point P of the screen. Therefore, anlight beam L_(e) ^(j,g,k+1) indicates that the light beam exits from thescreen 20, emitted in direction g from module j, touching (in this caseemerging from) the k+1-th screen point P.

[0080] In addition the apparatus has a screen 20 lighting system. Thissystem contains modules for generating light beams L_(d) and, The lightbeams L_(e) are associated to multiple different points of the screen20, and they are also associated to different emitting directions E ofthe screen points D. For example, in the embodiment in FIG. 3essentially the device 45 constitutes a module and the light beams L_(d)¹-L_(d) ^(n) emitted by the j-th device 45 _(j) pass through thedifferent screen points P_(k−2), . . . ,P_(k+2) of the screen 20. It isalso visible that as a continuation of every light beam L_(d) ¹-L_(d)^(n) light beams L_(c) ^(j,l,k−2), L_(c) ^(k,i,k−1), L_(c) ^(j,m,k),L_(c) ^(j,g,k+1), L_(c) ^(j,n,k+2) exit from the screen 20, propagatingin different E₁-E_(n*) emitting directions. At the same time, lightreaches the same screen point from other modules, for example in FIG. 3,where light beam L_(d) ¹ emerging from the j−1-th module 45 _(j−1) alsoreaches screen point P_(k+1) and emerges in a different direction E thanlight beam L_(d) ^(g) coming from the device 45 _(j) of the j-th module.So, in other words, the individual modules are realised as means forgenerating light beams L_(c) being emitted in different directionsE₁-E_(n*) from the screen points P, and for projecting light beams L_(d)¹-L_(d) ^(n) with different intensity and/or colour towards theindividual screen points P from different directions. For betterunderstanding, in FIG. 3 n=5, that is one module emits light in fivedifferent directions that reach five different screen points P. Theindividual modules of the apparatus are controlled by the appropriatecontrolling system according to the principles explained below.

[0081] The function of the modules, that is the 45 devices, which act asmeans for generating light beams, was performed in known solutions bylight sources S positioned on a light emitting surface 10 at earlierversions (see FIGS. 1 and 2). The function of these light sources S isto emit light from the screen points P of the screen 20 in differentemitting directions within the emitting angle range α, with appropriateintensity and/or colour from the given screen point P towards thedifferent emitting directions. The light sources S emit light in anangle range β. This angle range β essentially corresponds to theemission angle range α of the screen 20. As seen in FIG. 1, light sourceS₁, S₂, S₃, . . . , S_(n) emits an light beam L_(d) to screen point P₃and the direction of the light beams L_(e) emerging from screen point P₃will be determined by the mutual position of the individual lightsources S₁-S_(n) and screen point P₃.

[0082] The essence of the present invention is actually a possiblerealisation of these light sources S, or more exactly the provision ofan optical arrangement that can realise the functions provided by lightsources S having an ideally zero width.

[0083] As in the case of the documents referred to, we demonstrate theoperation of the invention by representing an arbitrarily selectedhorizontal line of screen points P and light sources S. It is understoodthat there are several lines of horizontal screen points when the realimage is created and similarly the light beams emerging from the imagegenerating means also emerge in several horizontal lines. The opticalsystem then images the light beams to the appropriate horizontal linesof the screen.

[0084] The light beams L_(c) creating the views associated to thedifferent E₁-E_(n*) emitting directions from the individual screenpoints P and associated to several different screen points P of thescreen 20 of the inventive apparatus are generated in the following way:

[0085] There are two-dimensional displays, in this case a 50microdisplay in the individual modules. This 50 microdisplay istypically an LCD panel. There is a lens in the modules imaging thepixels C_(d) of the display 50 to the screen 20 simultaneously, that isthe lens images the whole display 50 to the screen 20 simultaneously. Inthe two-dimensional display 50 the pixels C_(d) are associated to thedifferent screen points P and they are also associated to the differentemitting directions E¹-E^(n*) of the screen 20. The pixels C_(d)generate the light beams L_(c) essentially simultaneously, withdifferent co-ordinates, but substantially without any informationconcerning their emitting direction. The emitting direction associatedto the light beams L_(c) is only realised when the 40 imaging optics ofthe module 45 deflects the light beams L_(d) into deflection directionsD¹-D^(n). The light beams L_(d) propagating in the deflection directionsD¹-D^(n) pass the screen 20 substantially without changing theirdirection, so that the individual emitting directions E are actuallydetermined by the deflection directions D of the light beams L_(d)emerging from the module 45. It is visible that the light beams emergingfrom the j-th display 50 j are substantially parallel, that is the lightbeams L_(c) ¹-L_(c) ^(n) coming from the 50 j display are not in theappropriate angle, i.e. they are not deflected towards the deflectiondirection D, which are themselves associated to emitting directions E.The deflection is first performed by the optics after the 50 display,because the 40 imaging optics associated to the individual displays 50are designed for imaging substantially simultaneously the light beamsL_(c) generated by the pixels C_(d) with different co-ordinates intodifferent emitting directions E¹-E^(n*) or imaging directions.

[0086] To be more precise, the individual two-dimensional display 50 areregarded as image generating means, that generate complex images ofdetails to be projected to the emitting directions E from the differentscreen points P. At the same time the imaging optics functions as anoptical deflecting device diverting the light beams L_(c) incident onthe imaging optics, in a given angle depending on the co-ordinates ofincidence. In the case of the shown embodiment the imaging opticsconsists of optical lenses 40. At the same time, the lighting system hasmeans for generating substantially parallel and substantiallyunmodulated light beams L_(c). This means for generating the paralleland unmodulated light beams is the collimator 60 in the case of theembodiment in FIG. 3. The apparatus has an optical system that projectsthe image generating means—the display 50—with substantially parallellight beams L_(c) to an optical deflection means, in this case anoptical lens 40. As explained below, the optical deflection means, thatis the optical lens 40 in the optical system and the screen 20 arepositioned relative to each other so that the light beams L_(c) aredeflected in the deflection directions D towards the appropriate screenpoints P by the optical deflection means, i.e. the optical lens 40. Theindividual deflection directions D are practically analogous to thedifferent emitting directions E. The light beams L_(c) are modulated bythe information encoded in the details, that is pixels C_(d) of thecomposite image produced by the image generating means, i.e. the 50display.

[0087] In other words, the light beam generating means 45 projectinglight beams L_(d) to the screen points P has an image generating meansthat produces a composite image from the image details to be projectedfrom the different screen points P to the different emitting directionsE. This image generating means is the 50 microdisplay in FIG. 3, where acomposite image is created in a way elaborated below.

[0088] Therefore, an essential element of the apparatus is the opticaldeflecting device diverting the incident light beams L_(c) in a givenangle depending on the co-ordinates of incidence. This deflecting deviceis an optical lens 40 in this design, which in reality is carried out bya system of preferably plastic lenses with aspherical, or possiblydiffractive surfaces, with an eye on the possibility of mass production.Another part of the apparatus is the means for generating substantiallyparallel and substantially unmodulated light beams L_(c). This is, asmentioned above, in the case of the embodiment in FIG. 3 a collimator 60that produces collimated light beams L_(c) from divergent light beamsL_(s) emerging from a point light source 70. The expression“substantially parallel” means that the optical system has no focusbetween the collimator 60 and the optical lens 40, but a minutedivergence or convergence of light beams L_(c) is possible. By theexpression “homogenous as a function of the spatial co-ordinates” it ismeant that the light beams L_(c) are substantially unmodulated in thefunction of their three-dimensional co-ordinates. In other words, theirintensity and usually their colour is practically equal, according tothe fact that the intensity and colour modulation of the light beamsL_(c) will be performed first by the 50 display, when the light beamsL_(c) pass through it.

[0089] As it is shown in FIG. 3, the light of the light source 70 s isprovided by the common light source 80, which is distributed to the 70individual light sources by the 75 optical fibre wires selected from thebundle 76 of optical fibre wires. Naturally, it is also possible thatthe 70 individual light sources have their own light. valid lamps may beapplied as a common light source 80, such as those from the OSRAM HTIseries.

[0090] The apparatus according to the invention comprises an opticalsystem which projects the image produced by the individual displaydevices (i.e. the 50 display) to the optical deflecting means (i.e. theoptical lens 40) with substantially parallel light beams L_(c). In theoptical system, the optical deflecting means, i.e. the optical lens 40,and the screen 20 are positioned relative to each other so that thelight beams L_(d) are deflected from different deflection directions Dto the appropriate screen points P of the 20 display, where, as shownabove, the light beams L_(d) modulated first with the information codedin the individual image details of the complex image, by the 50 displayas an image generating means, and secondly, the light beams L_(d) aredeflected by the optical lens 40, as an optical deflecting means. Thus,the light beams L_(d) are modulated by the information coded with theindividual pixels (i.e. by the information carried by the pixels) of theimage generated by the displays 50, as a image generating means. Theoptical deflecting means, i.e. the optical lens 40, deflects the lightbeams L_(d) in the different deflection directions D to the screenpoints P corresponding to the mutual position of the appropriate modules45 and the screen 20. The modules 45 are positioned periodically shiftedand to optically equal or optically symmetrical positions in relation toeach other and the screen. The term ‘optically equal’ means that the 45individual modules include identical optical systems and they areshifted or sometimes rotated in relation to the screen with regularperiodicity.

[0091] It is perceivable that the optical deflection means, the opticallens 40, acts as a deflecting means which deflects the incident lightbeams L_(c) with a given angle, depending on the co-ordinates of theincidence. As illustrated in FIG. 3, the light beam L_(c) ¹ passingthrough the pixel C_(d) ^(j,l) at the left edge of the 50 _(j) SLM willbe deflected to a deflection direction D_(l) which is different from thedeflection direction D_(m) of the light beam L_(c) ^(m) passing throughthe pixel C_(d) ^(j,m) in the middle part of the 50 j SLM, which passesthrough the screen 20 in the Em emitting direction, in accordance withthe fact that the E_(m) emitting direction is determined by the D_(m)deflection direction. It is also clear from FIG. 3 (see also FIGS. 1 and2), that, because of the different deflection directions, the lightbeams L_(d) deflected to different deflection directions D₁-D_(n) by thecommon 40 _(j) optical lens pass through different screen points P. Inthis instance this means that the light beam L_(d) ^(m) propagating inthe direction D_(m) passes through the screen point P_(k) and the lightbeam L_(d) ¹ advancing in the direction D_(l) passes through the screenpoint P_(k−2). From the above it is also clear that the individualdisplays 50 generate a composite image which is not identical with anyreal image that the apparatus projects to any direction, because lightbeams passing through adjacent screen points of the display 50 do notnecessarily arrive at two adjacent screen points P on screen 20 as well.Even if this is the case, owing to the imaging system, such adjacentlight beams will practically leave the screen 20 in two differentdirections E, so they must be coded on the display 50 with informationcorresponding to different emitting directions E. Actually, viewing thescreen 20 from a region, namely from one of the directions opposite theemitting direction E, those light beams L_(e) which reach the observer'seye, and which are associated to different screen points P on the screen20, usually pass through and are modulated by different displays 50.Considering that within the emitting angle range α, determined by theemitting directions E, light is emitted in practically all directions.Therefore, when viewing the screen 20 from this region, light beamsreach the observer's eye from all screen points P (also see FIG. 5.).Thus the emitting angle range a is practically identical with thecomplete viewing angle region, i.e. with the angle region within whichthe light beams from screen points P reach the eyes of the observerlooking at the screen 20, or more simply, this is the region from wherethe observer is able to perceive some sort of image on the screen 20.

[0092] The principles of imaging are explained in more detail in thefollowing:

[0093] In the emitting angle range α the individual light beams L,propagate in well determined emitting directions E. Viewing the screen20 from a direction opposite these emitting directions E, light beamsleaving the individual screen points P may be seen, and therefore acomplete image is perceived on the whole of the screen 20, this completeimage being composed of the screen points P. It must be noted that inthe image appearing for the observer the surface of the screen and thescreen points P themselves may not necessarily be perceived, and theimage perceived will not be seen by the observer as a two dimensionalprojection of view, but the observer is more likely to feel real space.

[0094] For example it is presented in FIG. 3., that the light beamsL_(e)^(j − 1, i, k + 2), L_(e)^(j, i, k − 1)

[0095] from the P_(k+2), P_(k−1) screen points exit in the emittingdirection E_(i). Although it is not shown, a light beam L_(c) leaveseach screen points P in all directions E, so there are light beamsexiting from the screen points P_(k+1), P_(k), P_(k−2) in the directionE_(i) as well.

[0096] Accordingly, viewing the screen 20 from a direction opposite theemitting direction E_(i), the observer will see light of specific colourand intensity arriving from the screen pointsP_(k+2),P_(k+1),P_(k),P_(k−1),P_(k−2), and so the observer will perceivethe image created by the screen points P_(k+2), . . . ,P_(k−2). In thesame way, it may also be observed in FIG. 3. that the light beamsL_(e)^(j − 1, l, k + 1), L_(e)^(j, l, k − 2)

[0097] exit in the emitting direction E₁ from the screen points P_(k+1),P_(k−2). Similarly, light beams leave the other screen points P_(k+2),P_(k), P_(k−1) in the emitting direction E_(l) as well; for betteroverview of the figure, these are not shown. Thus, viewing the screen 20from a direction opposite the emitting direction E_(i), the observerwill see light of specific colour and intensity in the screen pointsP_(k+2),P_(k+1),P_(k),P_(k−1),P_(k−2), i.e. the observer will perceivethe image generated by the screen points P_(k+2), . . . ,P_(k−2).However, it is easily seen from the following that the image perceivablefrom a direction opposite the direction E_(l) emitting direction willusually be different from the image perceivable from a directionopposite the E_(i) emitting direction. This means that the screen 20 isable to provide different perceivable pictures from differentdirections. It may be seen that the light beam L_(e)^(j − 1, g, k + 2)

[0098] leaving screen point P_(k+1) is modulated by the pixel C_(d) ^(g)of the 50 _(j) display, while the light beam L_(e)^(j − 1, l, k + 1),

[0099] also leaving screen point P_(k+1), is modulated by the firstpixel C_(d)^(j − 1, l)

[0100] of the 50 _(j−1) display. Accordingly, the screen 20 is able toproduce different pictures from different directions, which means thatit can display three-dimensional pictures.

[0101] It is well shown in FIG. 5. that the great number of modules 45behind the screen 20 and the given divergence of the screen 20 make surethat a light beam arrives to the eyes of the observer from all screenpoints P, which results in the observer perceiving a continuous imagewithin the angular region. As it is shown separately on the right handside of the FIG. 5., the light beamsL_(e)^(g − 1), L_(e)^(g − 1), L_(e)^(g + 1)-

[0102] which reach the screen 20 as collimated non-divergent beams—leavethe screen point P in different directions. These beams are dispersed bythe screen 20 with the angle δ_(x), making them slightly divergent. Thisway light reaches the eyes E_(2L) of the observer even though thedirection of the light beams L_(e)^(g − 1), L_(e)^(g)

[0103] had originally missed the observer' eyes. It may be seen that thelight beam L_(e) ^(δg) reaching the observer's eyes E_(2L) seems to bethe continuation of the virtual light beam L_(e)^(δ  g^(′)),

[0104] which itself seem to start from between two modules 45 and passthrough the P screen point. This way there is no “gap” between the lightbeams L_(e)^(g − 1), L_(e)^(g), L_(e)^(g + 1),

[0105] the visually perceived image is not flawed with unlit parts, andthe viewing region is continuously covered.

[0106] It also seen that the complete view associated to the individualviewing directions is not produced by one module, but by severalmodules. With other systems, the creation of the complete view belongingto one certain view by one optical unit leads to abrupt, disturbingchanges, which may be observable in cases of unavoidable changes in theimage when the viewing point is changed. On the contrary, in thearrangement described in the invention, the image seen from any pointrepresented by the eyes E_(1L), E_(1R) of the observer is created byseveral modules. For example, with an arrangement providing horizontalparallax in practice, each image associated to a viewing directions iscreated by a large number of 25 vertical strips, the strips beingassociated to the individual modules (see also FIG. 7b.). The 25 stripesabut each other. This image arrangement ensures that if the observerchanges position, and his viewing point changes, for example, by movingin the direction of the F arrow, the light beamsL_(e)^(g − 1), L_(e)^(g1), L_(e)^(g + 1)

[0107] and the light beams L_(d)^(g − 1), L_(d)^(g), L_(d)^(g + 1)

[0108] of the modules are changed continuously, creating the imageperceived by the E_(2L) eye, the position of which is continuouslychanging. In this manner, a continuously changing image is created, inaccordance with the fact that theL_(d)^(g − 1), L_(d)^(g), L_(d)^(g + 1)

[0109] light beams are created by different modules 45. It is alsoclearly shown that beams from different modules 45 reach the right eyeE_(R) and the left eye E_(L) of the observer from the individual screenpoints P_(k−1), P_(k), P_(k+1), P_(k+2) etc. This basically means thatthe same screen point is able to transmit different information for theleft and right eye.

[0110] The same effect is represented in an even more detailed fashionin FIG. 6. In this figure we present how the apparatus described in theinvention displays different dimensional figures. As an example, in FIG.6, the apparatus displays two dark point objects O₁ and O₂ and two lightpoint objects O₃ and O₄, which are perceived as three dimensional fortwo observers. For better understanding we primarily indicated thoselight beams of the modules 45 which actually reached the eyes of theobservers, but it must be emphasised that there are light beams leavingall modules in all emitting directions. Therefore the apparatus isindependent of the position of the observers and provides a real 3Dimage when viewed from any direction within the view range. As opposedto the simply stereoscopic systems (handling the left and the right eye)or the multiview systems (changing images abruptly), the apparatusoffers a perfect movement parallax, the continuous image may be “walkedaround” by several observers within the view range, and the observersmay look behind the objects, where hidden details may also appear.

[0111] In FIG. 6, for example, it is shown that, the first observer willperceive the dark object O₁ with both eyes E_(1R) and E_(1L), but toachieve this the module 45 _(i−8) transmits a light beam to the righteye E_(1R), while the light beam to left eye E_(1L) is transmitted bythe module 45 _(i). This way the observer will clearly perceive that thelight from the object reaches his two eyes from different angles, andhe/she will also perceive the distance from the object O₁. Not only doesthe first observer perceive the object O₂ as well, but he/she can alsosense that for him/her the object O₂ is behind the object O₁, becausethe observer only receives information about the object O₂ throughhis/her E_(1L) left eye, through the light transmitted by the module 45_(i−2) in the direction of the left eye E_(1L). At the same time, forthe second observer the objects O₁ and O₂ will appear as two distinctobjects, according to the light beams reaching his/her eyes E_(2R) andE_(2L) from the modules 45 _(i+17) and 45 _(i16), and the module 45_(i+8). The left eye E_(2L) of the second observer cannot see the objectO₁, because the light beams arriving from its direction cannot beproduced by any of the modules. On the other hand, on the basis of thesame principles, both observers will see the point objects O₃ and O₄.For example, the light object O₄ will be perceived by both eyes of thefirst observer on the basis of the light exiting the modules 45 _(i+3)and 45 _(i), and the modules 45 _(i−8) and 45 _(i−11). It is noted thatowing to light beams, which may be emitted in different directions andwith different intensity, the same module 45 _(i), for example, is ableto display a different colour object for the firs observer's right eyeE_(1R) and left eye E_(1L). The right eye E_(2R) of the second observerdoes not perceive the object O₄, because it is obstructed by the objectO₂. The second observer can only see the object O₄ with his/her left eyeE_(2L). It is perceivable that the apparatus is capable of displayingany number of point objects of this sort, and this way it is alsosuitable for displaying objects of finite dimensions, since theseobjects may all be displayed as sets of points. We can also see thatobjects in front of and behind the screen 20 can equally be displayedwith the help of the apparatus. The light beams produced by theapparatus are exactly the same as if they had started from the object tobe displayed, and the apparatus does not take into consideration theposition of the observer, and a real image is displayed in alldirections within the emitting angle range, regardless of the positionof the observer. It is emphasised here again that the apparatuscontinuously emits light beams in directions where there are no viewersat all. Such light beams are represented in FIG. 6 as light beams L_(e).

[0112] From the above, it is clear that in accordance with the inventivemethod three dimensional images are displayed by generating light beamsL_(d) (or more precisely, light beams Le as the continuation of theselight beams L_(d)), the light beams L_(d) creating different viewsassociated to different emitting directions E of the individual screenpoints P. The light beams L_(d) are projected onto a directionselectively transmitting and/or reflecting screen 20. During the method,substantially simultaneously light beams L_(c) are generated with thepixels C_(d) of a two-dimensional display 50. These light beams L_(c)have substantially no information about their emitting direction E. Thepixels C_(d) have different co-ordinates. The light beams L areassociated to the different points P on the screen 20 and correspond tothe different emitting directions E of the screen points P. The lightbeams L_(c) generated by the pixels C_(d) with different co-ordinatesare imaged substantially simultaneously into different deflectingdirections D. The imaging is performed as a function of the co-ordinatesof the pixels C_(d) generating the light beams L_(c).

[0113] The light beams L_(c) emitted in different emission directions Efrom the screen points P are normally created by sending light beamsL_(d) with different colour and/or intensity from different directionsto the individual screen points P of the screen 20, and letting theL_(d) light beams through the screen 20 without actually changing theirdirection. It is perceivable that the procedure described in theinvention may also be fulfilled, by the mirror-like reflection of thelight beams L_(d) from the screen 20 as shown, for example, in FIG. 39.By the term “mirror-like” it is meant that the light beam L_(d) fallingon the screen 20 at a certain angle will be reflected at a substantiallyidentical angle, the same way as light beams are generally reflected bya normal plane mirror or a retroreflector. Additionally, it isemphasised that by the term “mirror-like” also covers the case when thereflection is retroflective along at least one dimension. This meansthat not considering the component of the direction vector of the inputlight beam, which is orthogonal to the screen surface, at least onefurther component will not change sign when comparing the directionvectors characterising the direction of the input and exit light beams.With a normal mirror, the incident and exit planes orthogonal to thescreen surface are the same, and both components of the vectorcharacterising the input direction which are parallel with the surfaceof the screen remain unchanged. With a retroreflector, both componentsof the vector characterising the input direction which are parallel withthe surface of the screen change sign. If the screen is onlyretroreflective in one direction, only one of the components beingparallel with the screen will change sign.

[0114] Thus the light beams L_(d) with different directions which are tobe emitted to the screen points P are produced by creating a compositeimage from the image details projected towards the different emittingdirections E from the different screen points P with the help of theimage generating means, i.e. the 50 display. This composite image isrealised by the providing the driver circuits 100 of the display 50 withappropriate input data. (see FIGS. 8. and 10.). A suitable programcreates the input data, i.e. distributes the image details to thedrivers of the individual displays 50, as shown in FIG. 4. The imagedetails constitute the images which are associated to a particularviewing direction of the three dimensional image. The image created onthe 50 display is illuminated by substantially parallel light beamsL_(c). In this manner, substantially parallel light beams L_(c) aregenerated, which are modulated with the information coded in theindividual image details. These substantially parallel light beamsL_(c), which are now modulated with the appropriate image information,are projected onto the optical deflection means, which is the imagingoptical lens 40 in our case. The substantially parallel light beamsL_(c), which are now modulated with the image IS details of thecomposite image, are projected with the optical deflecting means (i.e.the optical lens 40) towards the appropriate screen points P. Thisprojection is performed by deflecting the light beams L_(c) intodifferent deflection directions D. The deflection directions D aredetermined according to the position of the relevant image details onthe composite image, and the imaging properties of the opticaldeflecting means. The appropriate screen points are thus defined by themutual position of the relevant modules 45 and the screen 20. Themodules 45 comprise the relevant optical deflecting means, namely theoptical lens 40.

[0115] Preferably, the display element, i.e. the 50 display, is amicrodisplay, ideally a ferroelectric liquid crystal display (FLCmicrodisplay), especially an ICFLC (integrated circuit ferroelectricliquid crystal). Other traditional liquid crystal displays may also beused, such as, the SONY LCX series, or transmission or reflectionpanels, such as the MicroDisplay Corp. MD640G1 or the Displaytech, Inc.LightCaster® SXGA Display Panel. A further possibility is theapplication of light valve matrices based on other technologies.

[0116] It is must be mentioned that it is theoretically possible with ato generate with the image generating means so many image details, whichcorrespond to a number of directions which equals the number of emittingdirections of the individual screen points P. In this case as many imagegenerating means, i.e. displays 50 are necessary, as the number ofscreen points P in each line of the screen 20, because the total numberof light beams emitted from one line of the screen 20 must be equal tothe product of the number of screen points and emission directions. Thissolution, which is illustrated in FIG. 1, can only be carried out inpractice with difficulty, because in most cases the screen points P mustbe formed relatively close to each other, and accordingly, the displays50 would also have to be positioned in a way that the distance betweenthem is the same as the distance between the screen points P.

[0117] However, it may be feasible with certain displays applicationswith a large surface, such as billboards, scoreboards, etc., which areusually viewed from a greater distance, thus the distance between thescreen points may be significant as well, even several centimetres.

[0118] The practical solution generally applied with smaller devices isthat one image generating means produces a number of image details whichcorrespond to a number of directions which equals the multiple of thenumber of emitting directions E associated to the individual screenpoints P. In this manner, fewer image generating means are applied thanthe number of screen points P (see FIG. 2). This way we use the imagegenerating means to generate image details corresponding to the desirednumber of emitting directions E for several screen points P. Such anarrangement is actually shown in FIG. 3, It may be observed that thescreen points P are positioned more closely than the associated opticallens 40 and the displays 50. In other words, one display 50 has to“serve” several screen points P, usually on the basis of identical orsimilar directions, in order for a sufficient number of light beamsL_(e) to leave each screen point P in an appropriate number of emittingdirections E. When comparing FIGS. 1 and 2, it may be seen that, if thelight emitting surface 10 is positioned further from the screen 20, i.e.the distance between them is increased, the distance X_(s) between thelight sources S may be larger than the distance X_(p) between the screenpoints P. Owing to this solution, the size of the display 50 may belarger than the distance X_(p) between the screen points P. Thissolution is also described in detail in the document No. WO98/34411.

[0119] Apparently, if there is a p number of screen points P and thereis a q number of modules 45, and light beams L_(d) are leaving eachmodule in n deflection directions D, than a number n* of light beamsL_(e) can leave one screen point P, where n*=qn/p, since pn*=qn. As aresult of this, if we want to increase the number n* of emittingdirections, i.e. the angular resolution, when there is no change in theviewing angle, we must increase the number of modules (if the width ofthe device is given, we must position the devices more closely) orreduce the number of screen-screen points or increase the directionresolution of the modules. The increase of the number of modules may belimited by their size, and the reduction of the number of screen pointswould decrease the resolution of the image perceived. Thus displays withthe biggest possible pixel number must be applied in the modules 45.With moving pictures the formula is different, because the number oflight beams leaving each screen point must be provided within a set unittime. In this case, the following formula applies: n*f*=(qn/p) f, wheref* is the frame-frequency, which is usually 30 l/s, while f is the framefrequency of the display. Since the latter can be reasonably high, q maybe reduced this way, which means that a smaller number of fast displaysis required. A solution of this type is shown in FIG. 11.

[0120] It is clearly shown in FIG. 3 that the light beams L_(d)deflected by the optical lens 40 normally pass through a common focalpoint. These focal points may actually be regarded as if they wereforming a virtual light emitting surface 10′ with virtual light sourcesS′, which produce the light beams L_(d) with different direction andintensity.

[0121] The screen 20 shown in FIG. 4, as described in the document no.WO98/34411, provides the exiting light beams Le with a certaindivergence, for example by applying a holographic diffusing screen asthe screen 20. The screen 20 provides the substantially collimatedoutput beams leaving the screen points P with a divergence δx, with amaximum of few degrees, so that there is an overlap between the lightbeams L_(d)^(i), L_(d)^(i + 1)

[0122] arriving from the modules 45, which are practically the same asthe light beams L_(e)^(i), L_(e)^(i + 1)

[0123] belonging to adjacent emitting directions. Apparently, theoverlap, i.e. the tight contact of the adjacent light beamsL_(e)^(i), L_(e)^(i + 1)

[0124] appropriate, when the divergence angle δx is the same as theangle γ between the emitted light beams. This is shown in FIGS. 7.a-c.FIGS. 7a-c also illustrate that with arrangements without verticalparallax, when there is a horizontal divergence δx, a relatively bigvertical divergence δy is needed, otherwise the image would only beperceivable from a narrow horizontal strip.

[0125] It is shown in FIG. 7a. that the screen 20 is an optical platewhich produces a divergence at divergence angles δx, δy on the directionselectively transmitted and/or reflected light beams. Theoretically itis possible to form the screen 20 in a way that the necessary divergenceis generated on more surfaces, for example on its input and/or exitsurfaces, or the divergence may be provided by an additional diffusingscreen positioned on the screen 20. The application of further platesproviding mechanical protection or optical correction may be beneficial,such as the use of filters to improve contrast, and antireflectioncoating.

[0126] In theory the light emitting surface 10 may extend not onlyhorizontally, but vertically as well, which means that it may be dividedinto S light emitting points vertically, too. In this case the modules45 are not only placed in a horizontal position creating a viewassociated to a vertical parallax (as in FIG. 7b.), but the horizontallines of modules placed in different vertical positions create viewsbelonging to vertical parallaxes. In this case the individual lightbeams Le do not illuminate a 25 strip, but a 125 square (see FIG. 7c):This way a changing view from the screen 20 will be perceived not onlyby a horizontally moving observer, but also when the observer is movingup and down. This, however, is very difficult to accomplish technically.Therefore, in practice it is more simple if we discard the real verticalthree dimensional effect, and, similarly to the arrangement shown inFIG. 5., and the beams leaving the screen 20 are formed so that theemitted light beams leave in a vertically wide, but horizontally narrow25 strip (see also FIG. 7b). This solution is also described in detailin the document no. WO 94/23541.

[0127]FIG. 8. shows a practical embodiment of the 3D display apparatusrealising the horizontal parallax (represented conceptually in FIG.7.a), and the spatial arrangement of its parts. For reasons to beexplained later, the modules comprising the optical lens 40, the display50 and the collimator 60 are positioned in two horizontal lines. The twolines are shifted by a half period relative to each other. The opticalsystems containing the imaging optical lens 40, however, are formed sothat the modules of the lower and upper line image the 24 _(c) lightbeams from the 45 modules, which principally correspond to the L_(c)light beams, to the same horizontal 22, 23 screen lines. In the figureonly the bottom screen lines 23 and the top screen lines 22 arepresented, but naturally the screen 20 contains an appropriate number(e.g. 480) of horizontal lines. For instance, it is shown in FIG. 8 thatthe light beams 24 _(c) ^(f1) and 24 _(c) ^(a1) from the first module ofthe lower line fall on the same screen line 22, 23 as the light beams 24_(c) ^(f2) and 24 _(c) ^(a2) from the first module of the second line(the second module of the complete module series). The small-scalevertical difference in angles between the two light beams 24 _(c) fromthe two modules, which arise from the distance between the two lines ofmodules, does not cause any disturbance in the perception of thepicture, because, as it was shown in FIGS. 7 and 7.b, the beams 24 _(c)are already diffused at a great (approx. 100 degree) angle vertically.Therefore, the vertical deviation of the beams due to the differencebetween the lines of modules is practically negligible.

[0128] In FIG. 9 the optical system of a module can be seen in verticalcross-section. Although the imaging may appear similar to the horizontalcross-section shown in FIG. 3, the significant difference is that thepixels Cd₁-Cd_(z) belonging to one column of the display 50 belong tothe same image, i.e. the view perceivable from one particular direction.In other words, the vertical screen strip, which appears on the display50, will also appear in reality on the screen 20 as a simultaneouslyvisible screen strip, which is associated to a view seen from a certaindirection.

[0129] If an image must be displayed, which provides a spatial (3D) viewvertically as well, as many module lines are needed as the number of therequired emitting directions. In this case the arrangement of the pixelcolumns on the display 50 is carried out on the basis of the sameprinciples as the arrangement of the lines of the pixels C_(d), i.e. theindividual pixels of a pixel column belong to different verticalemitting directions. Also,—beside their horizontal divergence—, thevertical divergence of the light beams exiting from the screen 20 afterthe vertical diffusion by the screen 20 is significantly smaller (seeFIG. 7c), corresponding to the angle between the vertically adjacentmodules. This divergence is so small that there is no gap between thelight beams leaving in vertically adjacent directions, and the eyes ofan observer in any position will perceive a light beam.

[0130] In FIG. 10 a version of the device in FIG. 8 is shown which onlyincludes one line of modules 45, but otherwise the working principle isthe same. Usually, displays with a smaller horizontal dimension must beused for modules 45, which are arranged in one line. In order to obtainthe desired angle resolution, line of the modules (which is, in fact,constitutes the virtual light emitting surface 10′) must be placedfurther away from the screen 20, which requires displays 50 with largeresolution, and also imaging lenses in corresponding sizes and highresolution. At the same time, this arrangement is simpler optically andfrom a control point of view.

[0131]FIG. 10. shows the apparatus with a version of a further possibleilluminating system, which applies separate light sources 70, preferablyLED-s 71 illuminating in RGB colours, and an optical adapter for thehomogenising or collimating the light beams, preferably a micro lensmatrix or an internal reflection light concentrating element (thislatter is not indicated in FIG. 10). The LED-s 71 are on one commonsubstrate 69.

[0132] As an example, in FIG. 11. the optical system of a module can beseen in vertical cross-section, including a LED 70 and a internalreflection light-concentrating element, namely a pyramid-shaped 65mirror box.

[0133] As shown above, the number of light sources S and theirperiodicity fundamentally defines the angle resolution of the apparatus.If we increase the number of light sources S, while realising them withsmall physical size, a spatial (3D) image with good angle resolution andgreat depth of field may be generated. In the following parts examplesare shown, in order to demonstrate the principle of the apparatus.

[0134] FIGS. 12-15 show that a display 53 with larger size may generateseveral displays 50 ₁-50 ₄, or eventually several light sources S. Forexample, if a smaller resolution is sufficient on the screen 20, fourseparately controlled, 640×480 pixel display 50 ₁-50 ₄ may be formed onone 1600×1024 pixel display 53. In such a case the optical axis goingthrough the smaller displays 50 ₁-50 ₄ can be separated from each otherwith the help of known optical devices, such as prisms 41, and thepictures provided by the individual displays 50 ₁-50 ₄ may be projectedindependent of each other with the help of separate imaging lens 40. The43 and 44 oblique prisms (see FIGS. 14 and 15) may offer a similarsolution, if the optical axis only needs to be shifted marginally in thelateral direction, either horizontally or vertically. It concludes fromthe above that along the horizontal direction as many pixels arerequired as possible, since the three dimensional direction resolutionis determined by number of light beams leaving the individual pixels. Ifthere arc x screen points in the horizontal screen line, and an number nlight beams L_(c) can leave from each of them, than an x*n number ofpixels are required horizontally. In other words, the bigger the numberof pixels we are able to position and image on a given horizontal screenline, the greater the number of directions in which light beams may beemitted from each screen point, if the horizontal image resolution (thenumber of screen points P on a horizontal screen line) is fixed.

[0135]FIG. 16 shows that theoretically a display 52 offering a fasterframe frequency can replace more, slower displays 50 on the basis of thespot/sec requirements. In such cases the light sources 70 ₁-70 ₃illuminate alternately and synchronised with the frame frequency of thedisplay 52, and accordingly, the display 52 “serves” the virtual lightsources S′₁-S′₃ cyclically. The virtual light sources S′₁-S′₃ appearspatially separated, in accordance with the angle-based distinctionbetween the light sources 70 ₁-70 ₃ with separate collimators 60 ₁-60 ₃.The fast display 52, the lens focusing on the appropriate points of the10′ light emitting surface may be realised by a common imaging lens 46,as it is shown in FIG. 11, but it may also be realised by combiningseveral independent imaging systems.

[0136] In FIG. 17 we demonstrate that it is possible and even desirableto increase the number of display pixel available horizontally. In suchcases the two dimensional displays 50 should preferably be placed inseveral parallel lines shifted in relation to each other in thedirection parallel with the direction of the lines. Depending on therelation of the net width w_(n) and the gross width w_(g), and the hheight of the individual displays, the displays 50 may be placed in two,three or more lines so that there are more pixels available parallelwith the lines, typically in the horizontal direction. Following fromthe above, the horizontal shift w must be chosen in a way that thecentral optical axis of the individual displays 50 should be shifted byregular periods along the horizontal direction. This way it can beassured that the light beams laterally deflected by the lens 40 arriveat the appropriate screen-points P, and the emitting angles of the lightbeams L_(c) leaving the individual screen points P show regulardistribution.

[0137] Usually, but not necessarily, the shift w is chosen to be equalwith the quotient of the gross width w_(g) of the display 50 and thenumber of the lines created. Usually, the two line arrangement isoptimal, because if the 54 control outputs of the individual displays 50are IS set up and down, the displays 50 may be positioned so close thatan ideally continuous, long horizontal display may almost be achieved.

[0138]FIG. 3 depicts an arrangement, where the individual modules 45along the screen 20 are practically shifted along a straight lineparallel with the screen 20, but otherwise are at the same anglecompared to the screen 20 and they are optically completely equivalent.As opposed to this, we demonstrate on FIGS. 18-21 that the individualmodules 45 and the screen 20 can be also grouped in differentgeometrical arrangements.

[0139]FIG. 18 represents the principle of this optically uniformarrangement, which is especially advantageous from the point ofpractical implementation. The individual modules 45 are opticallyequivalent, i.e. contain the same 40 imaging lens. This makes massproduction of the modules 45 easier, and makes them interchangeable.Since they are shifted parallel with the screen 20 along a straightline, but are at the same angle to the screen 20, there is no opticalkeystone distortion related to the screen 20 and the optically symmetricarrangement of the modules 45 facilitates the collective imaging. Thearrangement can be freely expanded by selecting the number of themodules 45, therefore either 4:3, 16:9 or other displays with optionalproportions can be implemented.

[0140] The light beams arriving at the marginal P pixels can be also begenerated by closing the space laterally between the screen 20 and themodules 45 with a mirror M and return those beams L_(d) to the screenpoints P of the screen 20, which otherwise would not reach the screen20. The reflected beams can be regarded as if had been emitted by thevirtual modules 45 _(v). It can be demonstrated that the number of lightbeams L_(d) falling outside the screen 20 from the inner modules 45 isthe same which would have to be generated for the marginal screen pointsP with such virtual modules 45 _(v). Therefore, placing mirror M at theedge of the screen 20, the light beams heading outside the screen fromthe inner modules can be completely utilised and the total width of allthe modules 45 does not exceed the width of the screen 20, that is theapparatus may remain relatively compact in size.

[0141]FIG. 19 also demonstrates an example of an optically symmetricarrangement. Substituting shift along a parallel straight line with acylindrically symmetric transformation the modules 45 and the screen 20are arranged along a curve. For example, due to reasons of symmetry itis advantageous to arrange the screen 20 on a circular arc concentricwith one made up by the modules 45, as being demonstrated by thearrangement on FIG. 20. The screen 20 can be a cylindrical surface or aspherical surface advantageous from the point of projection. The radiusof the circular arc shaped screen 20 can be larger, equal or smallerthan the radius of the circular arc formed by the modules 45. Theproportion of the radiuses determines the number of modules having agiven size along the circumference, its distance from the screensurface, that is the relation of the angle resolution and imageresolution of the system. The arrangement can be extended to the wholecircular arc, that is to a 360° range, this way creating athree-dimensional view for the observer with a complete viewing angle.expediently for virtual reality systems or simulators. In large-scalesystems, like flight simulators, the modules can be advantageouslyrealised with projectors. The screen 20 can be reflective orretroflective, which is explained in detail in connection with FIGS. 28and 33-34.

[0142] The screen 20 can be made transmissive in the arc-shapedarrangement as demonstrated in FIG. 20. Since the range of the emittingangles towards the convex surface of the arc-shaped screen 20 is muchlarger than towards the concave side, it is also preferred to orient themodules 45 along the circular arc towards the common region, i.e. thecentre of the circular arc, the modules 45 and the screen 20 arepreferably arranged on the same side of the circular arc. The modules 45are preferably on circular arc with a larger radius, and the screen 20is on the circular arc with a smaller radius. The 35 observer will stillobserve the 3D image on the circumjacent screen on a wide-angle in the34 range. It is visible, that the central 45 c modules arc in anoptically equivalent position with the 45 p peripheral modules due tothe circular arrangement. The modules 45 and the screen 20 cantheoretically create a complete circular arc, where the screen 20 is acylindrical or a spherical surface.

[0143]FIG. 21 shows an optically asymmetric module-screen arrangement,where the screen and the modules are substantially lined up along astraight line, but the optical imaging of the modules are not the same;their angle with the screen 20 differs towards the edges and theirimaging is also asymmetric due to the uniform distribution of the Ppixels of the screen 20, usually showing a keystone distortion. Thecollective imaging can be realised where the image is pre-distorted bysoftware, so that that the optical distortion is compensated by thesoftware in this manner. However, due to the pixel character of theimages, disturbing effects may arise when the images of the adjacentmodules are combined.

[0144] We demonstrate the practical implementation of the optical systemof a module 45 in FIG. 22. The light source is the end 77 of an opticalfibre 75. The emerging light beams L_(c) are collimated by the firstaspherical lens 72 into a parallel beam. The beam passing through thedisplay 50 is focused by the second aspherical lens 73 to the lensaperture 74. After the spatial filtering by the lens 74 aperture thebeam angle of the divergent beams is increased by a dispersing lens 78.The dispersing lens 78 is a convex-concave lens the convex side of whichis towards the light source on the optical axis and its refractioncoefficient expediently differs from that of the lens 73 for colourcorrection. This optical system is designed so that the essentiallyuniformly distributed incident light beams L_(c) are deflectedessentially uniformly within the angle range β. However, the differenceof the deflection angles between central beams need to be relativelylarger, while the difference of the deflection angles between peripheralbeams are relatively smaller. This is necessary, so that the deflectedlight beams L_(d) defines uniformly distributed screen points P on thescreen 20, or correctly illuminates the physically predetermined screenpoints P.

[0145]FIG. 23 shows the front view of a large size 55 display, which hasthe complex images containing the image details to be projected in thedifferent emitting directions set next to each other along its long andnarrow effective area. The individual images can be regarded as if hadbeen created by a 50′ virtual display. This solution enables the 50′virtual displays to be placed tightly next to each other. FIG. 24 showsa top view of the 55 display together with the 40 lenses, which areintegrated into a collective 42 optical plate. The 40 lenses perform theimaging of the individual 50′ virtual displays, i.e. the imaging of theadjacent images generated by the 55 display.

[0146] FIGS. 25-26 demonstrate the possible configuration of the opticalsystem of the modules 45 if the displays 56 operate not in atransmission, but reflection mode.

[0147] It is expedient here to use for 56 display such micro-mechanicaldisplays, where the light is deflected by reflecting plates operated byintegrated circuit technology or by moving band-like structures behavingas optical gratings. Such a solution is the micro-mirror matrix of theDMD chip from Texas Instruments. According to the beam path in FIG. 25,the light is projected on the display 56 via the divider prism 57 fromthe collimator 60 and reflected from that to the divider prism 57towards the optical lens 40. Preferably, the divider prism 57 is a knownpolarising divider prism for LC micro-displays or a totally reflecting(TIR) prism for the micro-mechanical displays.

[0148]FIG. 26 displays a variety where the role of the 57 dividing prismis taken over by the semi-transparent plates8. Both versions can bebuilt by using a common, long display 55 and single, long divider prism57′. The latter version is displayed on FIG. 27. Similarly to thedisplay 55 in FIG. 23, the display 55′ can have a single, commoneffective area, where the displays of the individual modules are onlylogically separated, but it is also viable (as visible in FIG. 27) thatthe physically separate displays 56′ of the individual modules are fixedon a single, common base board 59.

[0149]FIG. 28 demonstrates the position of the modules 45 and the screen20, where similarly to FIG. 20 the screen 20 and the modules 45 arelocated along concentric circular arcs. It is important, however, thatthe screen 20 here is retroreflective, that is the incident light beamsare reflected towards the same direction. In order to be more precise,this feature of the screen 20 is only realised horizontally, in otherwords in the plane of FIG. 28. The vertical reflection from the screen20 is normal mirror-like, that is the incident angle is the same as theemergent angle, but the component of the light beam along the verticalplane remains constant. This is required, because otherwise the lightbeam would always be reflected to the modules 45 and would not reach theeyes of the observer.

[0150] An important feature of the arrangement in FIG. 28 is that due tothe arched, horizontally retroreflective screen 20 the diverging lightbeams emitted from the individual modules 45 converge again whenreflected and the whole surface of the screen 20 will be visible in arelatively narrow range 34, about the area around the head of the 35observer. To be more precise a three-dimensional view, which practicallycovers the area of the whole screen 20 is only generated in this range34. It is also visible that the centre of this 34 range is practicallythe common centre of the concentric circles created by the modules andthe screen 20. However, in this narrow 34 range the direction resolution(the angle resolution) of the 3D image will be high, because only with asmall lateral movement light beams can be observed emerging in differentdirections from the individual screen points. In other words, thedifferent angle views provided by the apparatus divide this narrow rangeamong each other, so the difference between the emitting directions willbe small. This means that the observed 3D effect will be very realistic,but there is no need to associate many emitting directions to theindividual screen points of the screen 20, which would otherwise requirea large number of modules or high-resolution displays in the individualmodules. It is also visible that as the observer moves closer to thescreen 20, the region covered by the emitting angle range of the screen20 becomes narrower. E.g. if the 35 observer moves into the position35′, only the light beams generated by the module 45 _(c) reach the eyesof the 35 observer, while the light beams from the marginal module 45_(p) avoid the observer.

[0151] The screen 20 is retroreflective, because its surface facing themodules 45 is covered with vertically aligned right-angled 26 prisms thehorizontal cross-section of which is depicted in the enlarged detail ofFIG. 28. A surface with such an embodiment is retroreflective in a givendirection, in a manner known per se (these directions are in a planebeing perpendicular to the longitudinal edge of the prisms). This meansthat the emitted light beams in these planes exit parallel to theincident light beams, but in the opposite direction.

[0152]FIG. 29 represents a practical application of the arrangement ofFIG. 28—a flight simulator. The three-dimensional view of the landscapeseen by the pilot appears on the screen 20, but this view will bevisible only for pilot 37 sitting in the cockpit 36, which simulates thecockpit of a real aeroplane. One or more projection units 46 behind andabove the cockpit 36 contain the modules 45 producing the light beamsthat produce the view for the pilot 37.

[0153]FIG. 30 presents the three-dimensional structure of a possiblerealisation of the screen 20 as well as the 30 a horizontal and 30 bvertical cross-sections for better demonstration. There is provides aseries of so-called lenticular tenses, i.e. cylindrical lenses withlarger radius of curvature on one surface and smaller radius ofcurvature on another surface of the screen 20. The cylindrical lenses 31with larger radius of curvature provide the smaller, approx. 1-2 degreehorizontal diffusion of the light beams L_(e), as depicted by the angleδx in FIG. 5 and FIG. 7a. The cylindrical lenses 32 with smaller radiusof curvature provide the larger, approx. 100 degree vertical diffusionof the light beams L_(e), as depicted by the angle δy in FIG. 7a. Thescreen 20 can be made of low cost, optical quality plastic with a knowntechnology, for example injection moulding. Diffusion can be achievedboth with a reflection screen 20 (see FIG. 31) and a transmission screenin a one or several layer structure. In the case of a reflection screenit is enough to produce cylindrical lenses that create half of thedesired diffusion, because due to reflection the light beams pass thescreen 20 twice and diffusion is achieved after the second pass.Theoretically, it is also possible to produce the optical surfacecreating both the horizontal and vertical diffusion on the same surfaceof the screen 20.

[0154]FIG. 32 depicts a version of the screen 20 where a holographiclayer 33 instead of cylindrical lenses achieves the desired diffusion ofthe light beams. The holographic layer 33 can create vertical andhorizontal diffusion at the same time, even to different extents.

[0155] In FIGS. 33 and 34, we demonstrate that a screen 20, which isretroreflective (in one dimension) can be produced by creatingright-angle prisms 26 on the screen 20 (see FIG. 28 as well). Theretroretlectivc effect is established in the plane perpendicular to thelongitudinal edge 27 of the prisms 26. Light beams on planes beingparallel with the longitudinal edge 27, or more exactly, the componentsof light beams falling in these planes arc reflected from the screen 20as a simple mirror. FIGS. 35 and 36 demonstrate that the 30 diffusingscreen or the holographic layer 33 placed in front of theretroreflective screen 20 provides the required divergence of theemitted light beams L_(c). FIG. 37 shows a version where the holographiclayer 33 is put directly on the retroreflective surface with anappropriate technology, for example replication.

[0156] We present a relatively simple embodiment of the 3D displayapparatus of the invention in FIG. 38. This apparatus only produces 3Dstill images and as such, it is excellent for advertising purposes, forexample. The projector 47 of the apparatus contains the modules (theseare not represented in FIG. 38) that emit the light beams L_(d)according to the above-described principles towards the screen 20, whichis usually positioned separately from the projector 47. There may be Mmirrors on both sides of the projector 47 if required, with the help ofwhich the width of the 47 projector can be reduced according to theprinciple described in connection with FIG. 19. The inner structure ofthe projector 47 of the apparatus in FIG. 38 is shown in FIG. 41 withthe difference that FIG. 38 contains a single line of modules, whileFIG. 41 depicts a double line arrangement.

[0157] The projector 47 and the screen 20 may be in a reflectionarrangement (see FIG. 39), that is the projector 47 can be fixed on theceiling 90 and the screen 20 can be installed on the wall (not shown inthe image) of the room. This arrangement is advantageous, because theprojector 47 can be positioned far from the screen 20. This arrangementcan provide 3D images with a good angle resolution and large depth offield. Namely, it is conceivable that the direction resolution of the 3Dimages, that is the angle between the adjacent emitting directions willbe determined by the distance between the screen 20 and the modules 45,and the distance between the individual modules 45. Observers watching ascreen 20 in reflection arrangement are in front of the screen 20compared to the projector 47 and under its plane, therefore a relativelylarge size screen 20 can be used in a relatively small room as well. Theapparatus provides a 3D view in front of and behind the screen 20 andthis way the rooms can be optically enlarged.

[0158] The screen 20 can also be made in a transmission version, that isthe light beams L_(d) emerging from the projector 47 pass through thescreen 20 and the light beams L_(e) emerging from the other side of thescreen reach the eyes of the observer. This arrangement is shown in FIG.40. In this case, the projector 47 need not be positioned higher thanthe observers, but can be placed at the same level or lower. Theadvantage of this arrangement is that the projector 47 can be in anotherroom, since the observers do not see the projector 47.

[0159]FIG. 41 shows the structure of the still image display 3Dapparatus. Since only still images can be projected, the role of thetwo-dimension displays in the projector 47 is taken over by a deviceprojecting a constant image, for example a 150 slide film, or in a givencase a reflection mode image carrier. The composite images 155 areimaged by lenses 40 on the screen 20, which may be closer or furtherfrom the projector 47. The composite images 155 are positioned in theappropriate geometry in the slide film 150, for example in a double linearrangement as shown in FIG. 41. Mirrors M can substitute the modulescreating the appropriate views of the edge screen points of the screenif required, as explained in FIG. 19. The images 155 in the slide film150 are lit from the back by light tubes 180 or incandescent bulbs knownfrom cinematic apparatus, or LEDs with an optional homogenising diffuseplate 185. The slide film 150 can be quickly and easily replaced ifanother image is to be displayed with the projector 47. A version of theautomatic mechanism effecting periodic replacements as known withalternating bulletin boards can also be applied. The individual complex155 images can be created on the slide film 150 with the appropriatemethods, with digital imaging technology, for example. The slide film issuitable to act as a two-dimension display, because small size colourimages with high resolution can be created and it essentially simulatesthe long and narrow effective area of the ideal large-size display shownin FIG. 23. The 3D display apparatus shown in FIG. 41 can bemanufactured simply and at a low cost, and it is capable of displayingexcellent quality pictures with 3D sensation.

[0160] It is noted that when the slide film 150 is lit through thediffuse sheet 185, not only the light beams perpendicular to the planeof the image 155 pass through the film 150, but other light beams withother directions as well. The 40 imaging optics with a relatively smallnumeric aperture can only image those beams which enter in a low coneangle, while the other, more oblique light beams are lost in the opticalsystem. In other words, the imaging lenses 40 practically make use ofthe approximately parallel light beams on the slide film 150. Therefore,it is also true in this case that in the projector 47 there is anoptical system projecting the images generated by the image generatingmeans—the 150 slide film with the 155 images in this case—to the opticaldeflecting means, that is the 40 imaging optical lens, with essentiallyparallel light beams. Based on the above, the system utilises the lightpassing the 155 images relatively inefficiently, but this is compensatedby that the brightness of the displayed 3D image is determined by thecumulated light output of the 155 images.

[0161]FIG. 42 shows another version of the optical imaging system usedin the modules 45. The 170 LED matrix provides the back lighting for the50 display. In order to archive the greatest brightness, the highestpossible number of light sources have to be placed behind the 50display. This can be achieved by fixing the non-cased LED chips on acommon substrate in a method known from the integrated circuittechnology and wire them together or to the appropriately designedoutput with a fine, usually gold metal thread (bonding). This way thechips can be placed every 0.4-0.5 mm, even a hundred of them behind anaverage size display. This way a perfectly homogenous, although costlylight source is provided, with extraordinary surface brightness, andwith good colour mixing and saturation. The marginal beams of thediverging beam emerging from the 170 LED chip matrix are absorbed whilepassing the small numeric aperture lenses 73 and 78 and substantiallythe light emerging perpendicular to the surface of the LED chip 170matrix is utilised in the system. The LED chip 170 matrix can bemulticoloured, e.g. the LEDs 171 of the usual RGB colours can be in theappropriate grouping as shown in FIGS. 43 and 44.

[0162] For better light utilisation, a beam forming collimating lens maybe provided between the LED chip matrix 170 and the display 50 tocollimate the outbound beams emitted in a wide angle. This beam formingcollimating lens may be expediently realised as a microlens matrix or aninternal reflection light integrating or light paralleling component, ina size identical with the chip matrix. Expediently, such a beam-shapingcomponent may be an expanding truncated pyramid shaped mirror box (seeFIG. 10) or a conically expanding plastic or glass component. In thismanner, the number of the chips can be reduced and standard RGB chipLEDs, for example Samsung or Marl made device can be used.

[0163] In the case of the RGB coloured LED illuminator shown in FIG. 44,the display 50 is monochrome and the consecutive colour images arecreated by the cyclical switching of the LEDs 170 belonging to the R, G,B colours. This may be done so that every colour is switched on oncewithin a {fraction (1/30)} s long frame. Evidently, this requires theappropriate frame frequency 50 display, i.e. in this case the images areto be displayed on the display 50 at about 90 l/s frequency. This waythe application of colour LCDs in the modules 45 can be avoided. In aknown manner, in colour panels large pixel numbers are used, with RGBfilters at third-resolution pixel triplets, or alternatively, three(RGB) individual panels are used in the colour LDC displays. In the caseof a display apparatus operating with parallel LCDs, a further triplingthe panels is not economic. Reducing the resolution of the display,however, results in the reduction of deflection directions, that is thedeterioration of direction resolution. Therefore, time sequential colourcontrol can be realised by using high-speed ferroelectric liquid crystal(FLC) panels and by framing the RGB images after each other with a3×framing frequency. As a further advantage, this results in a bettercolour mixing than the display with pixel-level colour mixing.

[0164] The display 50 may also be embodied by a LED or OLED display(organic LED). In this case, there is no need for a separate lightsource and a display. The LED or OLED display itself combines thefunctions of the light source and the image generating means. Beside thelight beams emitted in a parallel direction, there will be other beamsas well, but, as mentioned above, the deflecting optics will only imagethe substantially parallel beams onto the screen.

[0165]FIG. 45 shows a schematic layout of the control system of theapparatus. In the age of the convergence of broadcasting,telecommunication and computer technology the basic functions ofinformation systems, transfer, storing and processing of data arcessentially independent of whether the digital signals carry audio,visual or computer data. Modem apparatus, which can be integrated into asystem also has to be prepared accordingly so that it can handle anysignal, carrying 3D (visual or geometric model) information, possiblywithout the modification of the hardware. The monitors, televisions andother display devices generally handle input signals of differentstandards with dedicated circuits. Therefore, the control unit of theapparatus in the invention is basically configured as a computer 200, apersonal computer (PC) for example, so that it converts the inputdigital or analogue 3D data according to a given format or protocol ontoa standard computer bus 210, e.g. a PCI bus via input interface(expansion) cards. This configuration enables the subsequent creation ofnew physical inputs.

[0166] The input data of the system can originate from differentsources. As an example, we depicted a network interface 260, a wiremodem 270 and a radio/TV receiver unit 280 in FIG. 45, which all connectto the bus 210.

[0167] A camera 250 can be connected to the equipment via an input unit255, which provides data for self-calibration, head-tracking and themeasurement of environmental light conditions.

[0168] Following processing by the software 203, or directly, theincoming 3D data reaches the 3D unit 240 connected to the same bus 210,which is also physically configured as a (PCI) expansion card. The cardexpediently contains great complexity programmable logical ICs (FPGA).The task of the 3D unit 240 (3D Engine) is to produce the appropriatecomplex (module) image in real time and transfer it to the individual 45₁ . . . 45 _(q) modules

[0169] The functions of the computer 200 can also be realised withcontrol circuits 100 (see FIGS. 8 and 10), but the control circuits 100themselves generally only receive the data of the 3D unit 240 andcontrol the modules 45 on that basis.

[0170] The 3D unit 240 operates in different modes according to thedifferent input data:

[0171] Plane image display. It fills the appropriate pixels of thedisplays 50 of the 45 ₁ . . . 45 _(q) modules, so that the appropriate Ppixel of the screen 20 emit light beams in all directions with thecolour and intensity value of the given screen point of the recognisedtraditional standard 2D images.

[0172] The processing of images with views corresponding to differentviewing directions of any source, (computer generated or thephotographing or filming of natural views). The images may beuncompressed or decompressed. Using the necessary geometrical data, itcreates the composite (module) images by rearranging among each otherthe details of the images of different views.

[0173] The processing of a image provided with less views than theapparatus is able to display. For example, all the views the apparatuscan display are compiled from only five available aspects of an image.Although in theory, a large number of spatial images are required toreconstruct an essentially continuous 3D view. But the generation of allviews of different viewing directions is usually not economic,especially in the case of real imaging. Therefore, the 3D unit 240calculates the adequate number of intermediate views with the properalgorithms. Such solutions are known from U.S. Pat. No. 5,949,420 patentdescription, for example. The unit creates the composite (module) imageswith the same rearrangement as mentioned above, from the calculated,required number of intermediate views (and generally from the initialviews, as well).

[0174] The production of adequate number of 3D views from data of otherplatforms, such as DICOM, 3Dfx, VRML and other 3D CAD geometricalmodels. There is shown a 3Dfx module 230 as an example, which can beconnected to the bus 210 of the computer 200 in a known way as aseparate expansion card. A 3D software 203 of a known structure can beinstalled that creates the view image of adequate number and geometryfrom the described 3D object. The 3D unit 240 handles that similarly tothe above.

[0175] Thus the compatibility of the apparatus with any platform isprimarily the question of software. When setting the new standards, the3D information may be attached as supplementary data to the image with acentral viewing direction. In this manner, the 2D devices remaincompatible and can display 3D signals, naturally with a plane view imageonly.

[0176] In a special application, the hardware of the apparatus maycalculate the data of any intermediate view in real time. Therefore, itis possible to optimise the image perceived by the observer, accordingto the position of the two eyes of the observer. This means that onlytwo views of the image is projected towards the eyes of the observer.The adjacent views, i.e. the overlapping of the adjacent view images,which may be already visible due to the diffusion of the screen, areswitched off. In this manner, images with very good depth of field maybe created (high depth mode 3D image). It follows from the features ofthe inventive system that eye tracking and the above mentionedobserver-optimisation can be realised simultaneously for severalobservers. The control data for the eye tracking are provided by thecamera 250 or other dedicated hardware.

[0177] Another application possibility is when the hardware of theapparatus calculates any view in real time, it can intervene in theconstruction of the image and modify it. Such an option can be theconsideration of the environmental lights and lighting. Not only thebrightness can be adjusted, but also the light beams flickering on givenpoints of the objects, blurring shadows can be added. These are exactlythose effects, the lack of which makes the observer recognise that theperceived image is only an artificial image. Therefore, the addition ofthis option can create an extremely plastic, realistic view (Realitymode).

[0178] Three-dimensional images contain much more information than aplane image. It is suggested to use data compression methods whentransferring or storing 3D data. The similarity of the directional viewsof the images allows the use of effective compression methods. Thealgorithm already described above, namely the algorithm based on themanagement/increase of a small number of the directional views of theimages, utilising geometrical relations is an effective process toreduce data in itself. But it is worth using the already known imagecompression methods with the directional views of the images in order toachieve better compression. The decompression unit 220 is amulti-channel unit, operating according to a known standard, e.g. suchas MPEG2, MPEG4, Wavelet etc. The decompression unit 220 decompressesthe image content of the input compressed data flow and forwards theimages to the input of the 3D unit 240.

[0179] In addition, the computer 200 naturally controls all thefunctions of the apparatus, from the switch-on of the power supply 85 ofthe light source 80, through controlling of the cooling, to the displaymenu. The apparatus can carry out self-diagnostics and may performcertain servicing corrections and adjustments controlled via an IPconnected to the Internet, either through a telephone line or via acomputer network, if required.

1. An apparatus for displaying 3D images, the apparatus comprising a, ascreen for direction selectively transmitting and/or reflecting light,b, a screen illuminating system, the screen illuminating systemcomprising c, modules for generating light beams, the light beams beingassociated to multiple different points of the screen, and beingassociated to different emitting directions of the points of the screen,and further d, the screen providing divergence to the transmitted orreflected light, according to the angle between neighbouring emittingdirections, and the apparatus further comprising e, a control system forcontrolling the modules, characterised in that f, the modules furthercomprise a two-dimensional display, and g, an optical system forsimultaneously imaging the individual pixels of the display onto thescreen, where h, the display pixels on the two-dimensional displayassociated to the different points on the screen and corresponding tothe different emitting directions associated to the different screenpoints generate substantially simultaneously light beams with differentco-ordinates but substantially without emitting direction information,and i, the imaging optics associated to the display substantiallysimultaneously images the light beams generated by the display pixelswith different co-ordinates into different emitting directions orimaging directions.
 2. The apparatus of claim 1, characterised in thata, the screen (20) transmits the incoming light beams (L_(d))substantially without changing their direction or reflects the lightbeams in a mirror-like manner or retroreflectively, b, the modules arerealised as means for generating light beams (L_(e)) being emitted indifferent directions from the screen points (P) and for projecting lightbeams (L_(d)) with different intensity and/or colour towards theindividual screen points (P) from different directions (D), where in themeans for projecting light beams (L_(d)) towards the screen points (P)c, the two dimensional display (50) is realised as an image generatingmeans for generating light beams (L_(c)) to be projected towardsdifferent directions, where the light beams (L_(c)) associated to thedifferent projection directions are generated with different pixels(C_(d)) of the two dimensional display (50), and the imaging opticscomprises d, means for deflecting with a given angle the light beams(L_(c)) incoming onto the imaging optics as a function of the incomingco-ordinates, said means preferably being an optical lens, and furtherthe screen illuminating system comprises c, means for generatingsubstantially parallel, and—as a function of the spatialco-ordinates—substantially homogenous light beams for illuminating theimage generating means, and further f, the modules (45) are positionedin optically equivalent positions, periodically shifted relative to eachother and to the screen (20), so that g, the light beams (L_(c)) aredeflected by the optical deflecting means towards the differentdeflection directions (D) and towards the appropriate screen points (P),according to the mutual position of the relevant modules (45) and thescreen (20), the light beams (L_(c)) being coded with the pixels of acomposite image—preferably by modulating with colour- and intensityinformation—, where the composite image is generated by the imagegenerating means.
 3. The apparatus of claim 1 or 2, characterised inthat the two-dimensional display is a liquid crystal micro-display,particularly transmission or reflection mode LC micro-display, LED orOLED display, or micromechanical device, particularly micro-mirrormatrix, active optical grating or other light valve matrix.
 4. Theapparatus of any one of claims 1 to 3, characterised in that thetwo-dimensional displays create a composite image without verticalparallax information, and the modules are arranged in horizontal lines,and further the horizontal divergence (δy) of the screen corresponds tothe angle between light beams (L_(d)) projected onto the same screenpoint from neighbouring modules, and the vertical divergence (δy) of thescreen corresponds to the desired vertical viewing range.
 5. Theapparatus of any one of claims 1 to 4, characterised in that the modulesare arranged in multiple parallel lines, and shifted relative to eachother in a direction parallel to the lines.
 6. The apparatus of any oneof claims 1 to 5, characterised in that the illuminating system of theimage generating means comprises multiple means for generatingsubstantially parallel light beams (L_(c)), the means for generatingparallel light beams being illuminated by a common light source (80). 7.The apparatus of claim 6, characterised by comprising means formodulating the light of the common light source, preferably a rotatingcolour filter disk, or other light shutter, and the light of the commonlight source is guided to the individual modules with a light guide oroptical fibre.
 8. The apparatus of any one of claims 1 to 5,characterised by comprising multiple light sources, preferably LEDs,particularly a LED chip (170) matrix provided with multicolour LEDs, ormultiple separate LEDs, which are associated to the individual modules.9. The apparatus of claim 8, characterised in that the LEDs are providedwith a beam shaping adapter, preferably a microlens matrix or areflecting light integrating/concentrating element (65).
 10. Theapparatus of any one of claims 1 to 9, characterised in that the screenis an optical plate for providing divergence to the directionselectively transmitted and/or reflected light beams, the angle of thedivergence (δx,δy) corresponding to the angle between the light beamsoriginating from neighbouring modules (45) and emitting from the samescreen point (P), in the plane defined by the neighbouring modules (45)and the screen point (P).
 11. The apparatus of claim 10, characterisedin that the divergence of the optical plate is done with a lens system(30) or with a holographic layer (33).
 12. The apparatus of any one ofclaims 4 to 11, characterised in that the screen providing thedivergence has a horizontally retroreflective surface, particularly asurface with vertically oriented prism structure.
 13. The apparatus ofany one of claims 1 to 12, characterised in that the modules arearranged along a straight section parallel to the screen.
 14. Theapparatus of any one of claims 1 to 12, characterised in that themodules are arranged along a section of a circle, and the screen is acylindrical or spherical surface substantially concentric with thecircle of the modules.
 15. The apparatus of any one of claims 1 to 14,characterised in that the controlling means is realised as a computer,so that a, the apparatus functions as a network device according tostandards known per se, where the apparatus b, processes the inputsignals according to different standards, converted onto a computer databus.
 16. The apparatus of claim 15, characterised in that thecontrolling means autonomously stores and processes images, preferablyfor the purposes of image compression, optimisation according to viewingposition, realistic display modified according to the surroundingillumination.
 17. A method for the displaying of 3D images, comprisingthe steps of a, generating light beams (L_(d)) associated to multipledifferent points (P) of a screen (20), the light beams (L_(d)) creatingdifferent views associated to different emitting directions (E) of theindividual screen points (P), and b, projecting the light beams (L_(d))onto a direction selectively transmitting and/or reflecting screen (20),the screen (20) providing divergence (δx) corresponding to the anglebetween two neighbouring emitting directions (E), characterised by c,generating substantially simultaneously light beams (L_(c))substantially without emitting direction information with pixels (C_(d))of a two-dimensional display (50), the pixels (C_(d)) having differentco-ordinates, the light beams (L_(c)) being associated to the differentpoints (P) on the screen (20) and corresponding to the differentemitting directions (E) of the screen points (P), and d, imagingsubstantially simultaneously the light beams (L_(c)) generated by thedisplay pixels (C_(d)) with different co-ordinates into differentdeflecting directions (D), the imaging being performed as a function ofthe co-ordinates of the pixels (C_(d)) generating the light beams(L_(c)).
 18. The method of claim 17, characterised in that the lightbeams creating the different views are generated with the followingsteps: a, light having different intensity and/or colour is emitted intodifferent emitting directions from the points of the screen, where b,the light beams emitted from the screen points into different directionsare generated by projecting light beams with different intensity and/orcolour towards the individual screen points from different directions,and transmitting the light beams substantially without changing theirdirection or reflecting the light beams from the screen substantiallymaintaining the direction, while providing the appropriate divergence tothe light beams, and further c, the light beams projected in differentdirections towards the screen points are created by generating acomposite image, the composite image comprising image details, the imagedetails corresponding to the images to be projected into differentdirections from the different screen points, and d, illuminating thecomposite images with substantially parallel light beams, generatingsubstantially parallel light beams being modulated with the intensityand/or colour information of the individual image details, and e,projecting the substantially parallel light beams being thus modulatedas a function of the spatial co-ordinates onto an optical deflectingmeans, preferably onto an imaging optics, and f. projecting with theoptical deflecting means the substantially parallel light beams beingmodulated with the image details of the composite image towards theappropriate screen points, by deflecting the light beams into differentdirections, according to the position of the relevant image details onthe composite image, and the imaging properties of the opticaldeflecting element, the appropriate screen points being defined by themutual position of the relevant optical deflecting means and the screen.19. The method of claim 17 or 18, characterised in that the product ofthe number of the image generating means and the number of their pixelsequals the product of the number of the screen points and the number ofthe emitting directions associated to the screen points.
 20. The methodof any one of claims 17 to 19, characterised by generating one view ofthe 3D image which is seen from each single direction by several imagegenerating means.
 21. The method of any one of claims 17 to 20,characterised by generating a 3D image without vertical parallax frommultiple vertical image strips, the image strips being generated by theindividual image generating means.
 22. The method of any one of claims17 to 21, characterised by generating with one image generating meansmultiple image details corresponding to multiple of the number of theviewing directions associated to the individual screen points, andassociating fewer image generating means than the number of the screenpoints, so that with one image generating means image details aregenerated which are associated to substantially equal or neighbouringviewing directions of several screen points.
 23. The method of any oneof claims 17 to 21, characterised by generating with one imagegenerating means image details corresponding to the number of differentviewing directions of each screen point, and using as many imagegenerating means associated to one horizontal screen line as the numberof the screen points in that screen line.
 24. The method of any one ofclaims 17 to 23, characterised by using pixels with independent lightemitting properties in the image generating means.
 25. The method of anyone of claims 17 to 23, characterised by illuminating the imagegenerating means with separate light sources.
 26. The method of any oneof claims 17 to 23, characterised by illuminating multiple imagegenerating means with a common light source.
 27. The method of any oneof claims 17 to 23, characterised in creating a divergence of the lightbeams, the light beams being direction selectively transmitted throughthe screen and/or reflected from the screen, the angle of the divergencecorresponding to the angle between the light beams being emitted fromthe same screen point, in the plane determined by the light beamsemitted from that screen point.
 28. An apparatus for displaying 3Dimages, the apparatus comprising a, a screen for direction selectivelytransmitting and/or reflecting light, b, a screen illuminating system,the system comprising c, modules for generating light beams, the lightbeams being associated to multiple different points of the screen, andbeing associated to different emitting directions of the points of thescreen, and further d, the screen providing divergence to thetransmitted or reflected light, according to the angle betweenneighbouring emitting directions, characterised in that f, the modulesfurther comprise a two-dimensional image, and g, an optical system forsimultaneously imaging the individual image points of the image onto thescreen, where h, the image points of the two-dimensional imageassociated to the different points on the screen and corresponding tothe different emitting directions associated to the different screenpoints generate substantially simultaneously light beams with differentco-ordinates but substantially without emitting direction information,and i, the imaging optics associated to the display substantiallysimultaneously images the light beams generated by the image points withdifferent co-ordinates into different emitting directions or imagingdirections.
 29. The apparatus of claim 28, characterised in that theimage is contained on a slide strip (transparency strip) or other imagecarrier medium.
 30. The apparatus of claim 28 or 29, characterised bycomprising multiple light sources associated to the individual modules,preferably LED or incandescent lamp, or comprising a common light sourceilluminating the images, preferably a light tube.
 31. The apparatus ofany one of the claims 28 to 30, characterised in that the imaging opticsassociated to the images is realised as an optical plate embodied in asingle unit, preferably as a lens matrix.